House construction / Financing single-family house conceivable?

Does it necessarily have to be a detached house, or would a terraced house also be an option?

Hello.
It does not have to be a detached house. A semi-detached house or even a terraced house would also fit. A detached house with 120 sqm would also work, but it is probably not much cheaper, so it would fit the income.
As written in the first post, only such plots are currently offered, or even large 800 sqm ones, but we have no chance with those.
For me, it would even be better if it were a plot of about 350 sqm for a semi-detached house. Then we could probably at least buy the plot with equity.

Yes, let's see what comes onto the market.

Yes, that was exactly what I said. Just because you build 120 m² instead of 130 m² doesn't mean you save a huge amount of money. The semi-detached house is usually only cheaper because the plot of land can be smaller. The pure construction costs are quite similar to those of a detached house.

I didn't mean at all that one should be ashamed of a small house. From my point of view, the original poster doesn't have unrealistic expectations; it's just that a house below a certain size will simply be too small to live in sensibly (unless you implement a lot of clever detail solutions). In other words: a condominium with 100 m² can definitely be considered large. A single-family house with 100 m² of living space and no basement will be anything but spacious; quite the opposite. That's why a nice condominium might also be worth considering. Theoretically, it can always be sold in ten years and "exchanged" for a house.

A single-family house with 100 m² of living space and without a basement will be anything but spacious, but rather the exact opposite.

Well, I have one like that, for three people, plus a storage room... i.e. 100 m² for living including the hallway. It fits fine – of course it could be more spacious here and there, but it was also what I could afford and I am much more satisfied overall than in the rental apartment before. If you can manage 110 m², then with clever planning the extra 10 m² all go into actual living space, because you also have circulation areas in the small house. Seriously crazy, 1800 gross for full-time, a trained profession (graphic designer?), and that’s the acceptable limit? That’s really bitter. A project overall in the range up to max. 500k€ (i.e. if you subtract the equity, about 420k€ loan) should just barely be doable if you apply the moral rule "loan no more than 100 times net income." I have not included bonuses and 13th salary. If you can make it with that...

The gross salary mentioned here is certainly very low, but I also know that trained graphic designers in permanent employment tend to earn less. That's why many are also working freelance. With a small regular clientele, things go a bit better, although many clients also try to push down the daily rates. With social security through the KSK, however, it is quite possible to make a living.

A project overall in the range of up to max. €500k (i.e. if you deduct the equity, about €420k loan) should just still be feasible if you apply the moral rule "loan not more than 100x net income." I have not included bonus and 13th salary. If that is sufficient...

The calculation is something for banks but should not be used privately. Much more important would be a calculation of the monthly installment (house construction) and all other costs (realistic, rather too much than too little). If only €0-300 remain, then leave it. From €500 upwards, one could decide on building a house.

Yes, a household budget book or the overview of where the money goes (monthly, one-time items that appear spread over the year) is always useful. Almost €1000 cold rent and total housing costs of €1400 already constitute quite a substantial base. I come to almost the same number overall, and that includes all credit and additional costs, including property tax, internet already. Only no reserves yet.